解决velocity-tools-2.0中ViewTool接口被废除的情况
该问题请参考：
http://www.oschina.net/question/100267_20922
先把该帖子上的内容本分转过来，然后加上自己的解决方法
tsl0922说：“
初学Velocity，想写个VelocityTool类实现以相对路径方式嵌入动态页面，思路大致与http://www.oschina.net/code/snippet_12_694中一样，因为新版中init(Object arg0)方法已经Deprecated了，换用configure(Map props)(见http://velocity.apache.org/tools/devel/upgrading.html最下面和http://velocity.apache.org/tools/devel/creatingtools.html），代码如下：
import java.util.Map;
import org.apache.velocity.VelocityContext;
import org.apache.velocity.tools.view.ViewContext;
public class VelocityTool {
protected VelocityContext velocity;
public void configure(Map props) {
Object obj = props.get("velocityContext");
if (obj instanceof ViewContext) {
ViewContext viewContext = (ViewContext) obj;
velocity = (VelocityContext) viewContext.getVelocityContext();
}
}
public String cur_templete() {
return velocity.getCurrentTemplateName();
}
}经测试
public class VelocityTools {
private ViewContext context;
protected HttpServletRequest request;
public VelocityTools() {
System.out.println("sssssssssssssssssssssssssssssssssssss");
}
public void configure(Map props) {
Object obj = props.get("velocityContext");
if (obj instanceof ViewContext) {
context = (ViewContext) obj;
request = context.getRequest();
}
}
public void init(Object arg0) {
System.out.println("init");
// scope: request or session
if (arg0 instanceof ViewContext) {
System.out.println("vvvvvvvvvvvvvvvcccccccccccccccccccc");
}
// scope: application
else if (arg0 instanceof ServletContext) {
System.out.println("sssssssssssssssssssscccccccccccccccccccc");
}
}
}虽然ViewTool接口被去掉了，但是可以添加上方法：
public void init(Object arg0) 下面这段代码在apache的官网上有解释，英文不好，单仔细一看就明白了。
连接时相关问题的链接
http://velocity.apache.org/tools/devel/creatingtools.html
把apache官网上的话复制一下。
If you want to allow your tool to be configured, you have two options:
- add a public setter for each property
- add a public void configure(Map props) method
public VelocityTools() {
System.out.println("do constructor VelocityTools");
}
public void configure(Map props) {
Object obj = props.get("velocityContext");
if (obj instanceof ViewContext) {
context = (ViewContext) obj;
request = context.getRequest();
}
}obj instanceof ViewContext属性:deprecationSupportMode 默认是ture值。
而方法setDeprecationSupportMode(boolean support) 不赞成使用了
在createContext()方法中创建context的类型一定是ChainedContext
VelocityView.java
……
private boolean deprecationSupportMode = true;
……
@Deprecated
protected final void setDeprecationSupportMode(boolean support)
{
if (deprecationSupportMode != support)
{
this.deprecationSupportMode = support;
debug("deprecationSupportMode is now %s", (support ? "on" : "off"));
}
}
……
/**
* Creates and returns an initialized Velocity context.
*
* A new context of class {@link ViewToolContext} is created and
* initialized.
*
* @param request servlet request from client
* @param response servlet reponse to client
*/
@Override
public ViewToolContext createContext(HttpServletRequest request,
HttpServletResponse response)
{
ViewToolContext ctx;
if (this.deprecationSupportMode)
{
ctx = new ChainedContext(velocity, request, response, servletContext);
}
else
{
ctx = new ViewToolContext(velocity, request, response, servletContext);
}
prepareContext(ctx, request);
return ctx;
}protected Method getInit()
{
if (this.init == null)
{
try
{
// try to get an init(Object) method
this.init =
getToolClass().getMethod("init", new Class[]{ Object.class });
}
catch (NoSuchMethodException nsme)
{
// ignore
}
}
return this.init;
}附上代码清单
package org.apache.velocity.tools;
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
import java.lang.reflect.Method;
import java.util.Map;
import org.apache.velocity.tools.ToolContext;
/**
* Manages old tools which still use the deprecated init() method.
*
* @author Nathan Bubna
* @version $Id: OldToolInfo.java 674 2012-05-30 05:11:51Z liu_peng $
*/
public class OldToolInfo extends ToolInfo
{
private static final long serialVersionUID = -4062162635847288761L;
public static final String INIT_METHOD_NAME = "init";
private transient Method init;
/**
* Creates a new instance using the minimum required info
* necessary for a tool.
*/
public OldToolInfo(String key, Class clazz)
{
super(key, clazz);
}
protected Method getInit()
{
if (this.init == null)
{
try
{
// try to get an init(Object) method
this.init =
getToolClass().getMethod("init", new Class[]{ Object.class });
}
catch (NoSuchMethodException nsme)
{
// ignore
}
}
return this.init;
}
/**
*
*
* @param clazz the java.lang.Class of the tool
*/
@Override
public void setClass(Class clazz)
{
super.setClass(clazz);
// clear any existing init method
this.init = null;
}
@Override
protected void configure(Object tool, Map configuration)
{
// have specific setters and configure(Map) called first
super.configure(tool, configuration);
Method init = getInit();
if (init != null)
{
// ctx should, in all cases where a tool has such a method,
// actually be a View(Tool)Context, but we don't want to link
// to that class here, so as not to pollute the generic jar
Object ctx = configuration.get(ToolContext.CONTEXT_KEY);
if (ctx != null)
{
invoke(init, tool, ctx);
}
}
}
}